Carpathian Rotation During Slab Roll Back and Detachment

As part of a collaborative project focusing on Mediterranean geodynamics, we report paleomagnetic results that constrain the development of the Carpathian arc (Romania). While tectonic rotations are evaluated through analysis of paleomagnetic directions, age control on sedimentary formations is obtained using high-resolution magnetostratigraphy performed on several sections from the Eastern and the Southern Carpathians. In Badenian to Sarmatian strata (16.4-9.9 Ma), statistical analysis of paleomagnetic site-mean directions indicate ca. 30 degrees clockwise rotation of the Southern Carpathians while remagnetization is suggested by a negative fold test in the Eastern Carpathian. During Late Miocene to Early Pliocene, magnetostratigraphic results indicate over 7 km-thick continuous deposition between 7.0 and 2.5 constrained by unambiguous correlation to the astronomical polarity time-scale (APTS). These strata record no rotation indicating that the rotations stopped everywhere by 7.0 Ma except in the Bend Area between the Southern and the Eastern Carpathians where rotation still occurred after 5.4 Ma. Our results are compared to a compilation of existing Tertiary paleomagnetic data throughout the Carpathian orogen. The outcome of this analysis is interpreted in a three stage development of the Carpathian arc: (1) up to 80 degrees clockwise (counterclockwise) rotation of the Eastern (Western) Carpathians during early eastward slab roll back; (2) 30 degrees clockwise rotation of the Southern Carpathian during Sarmatian southward slab detachment and (3) recent rotation in the bend area associated to final slab detachment and break off. To understand slab-related processes driving arc development, the Carpathian arc is compared to the Calabrian, the Hellenic and Gibraltar arcs where similar tectonic rotation patterns are observed during the Neogene.